This invention relates to a method of, and apparatus for driving and lining tunnels. The term "tunnel" or "tunnels" used throughout this specification is intended to include galleries, underground roadways, trenches and similar elongate excavations.
In order to drive a tunnel, it is known to use a knife shield, that is to say a drive shield having a plurality of elongate planks (knives) mounted side-by-side on a support frame, the knives being advanceable, either singly or in groups, relative to the frame for driving the tunnel. Where a tunnel formed by such a knife shield is to be provided with a concrete lining, the knife shield is provided with shuttering at its rear, which enables the concreting work to be effected immediately behind the knife shield and simultaneously with the advance of the tunnel. One known apparatus for driving and lining tunnels utilises a knife shield whose knives are provided with tail extensions which together form an outer shuttering (see DT-OS 2522029). Inner shuttering is constitute by a tubular former which is coupled, via hydraulic rams, to the support frame of the knife shield, so that it can be advanced in accordance with the progress of the concreting work, the support frame acting as an abutment for this advance. In order to close the end of the annular space between the outer and inner shuttering. an end shuttering is provided, this end shuttering also being connected to the support frame in such a way that it can be advanced as the concreting proceeds.
With this apparatus, the tunnelling and the concreting (lining) can be rendered largely independent of each other. Unfortunately, such apparatus is both complicated and expensive. Moreover, when the tail extensions of the knives forming the outer shuttering are advanced, gaps are formed between the walls of the tunnel and the concrete lining introduced which may lead to undesirable subsidence.
The aim of the invention is to provide a method of, and apparatus for driving and lining tunnels, which substantially reduces the risk of subsidence, and which enables the concrete lining to be introduced immediately behind the tunnel drive shield so that the exposed tunnel wall can be rendered safe within a very short time.